The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Inkjet printers eject liquid ink through printhead nozzles to form characters and graphics on a medium such as paper. Printheads of inkjet printers are either scanning-type or page-wide array (PWA) type. FIGS. 1A and 1B help explain operational differences between scanning-type and PWA-type printheads. FIGS. 2A and 2B show arrangements of nozzles of scanning-type and PWA-type printheads, respectively. FIGS. 3A and 3B show exemplary inkjet printing systems that use scanning-type and PWA-type printheads, respectively.
Referring now to FIGS. 1A and 1B, a scanning-type printhead 10 and a PWA-type printhead 18 are shown, respectively. In FIG. 1A, the scanning-type printhead 10 is typically mounted on a set of rails (not shown) that are parallel to a printhead axis 12. The scanning-type printhead 10 reciprocally slides on the rails along the printhead axis 12 across a width of paper 14. While the scanning-type printhead 10 scans across the width of the paper 14, the paper 14 is held stationary, and ink droplets are ejected on the paper 14 through nozzles (not shown) to print a desired image. When the scanning-type printhead 10 has completed a sweep, the paper 14 is moved along a medium axis 16 that is perpendicular to the printhead axis 12, and the scanning-type printhead 10 begins a next sweep. During the next sweep, the scanning-type printhead 10 may print data on a new portion of the paper 14 and/or a portion where data was printed during a prior sweep.
In FIG. 1B, the position of the PWA-type printhead 18 is generally fixed. The PWA-type printhead 18 is as wide as the desired print area along the width of the paper 14. The paper 14 moves along the medium axis 16 that is perpendicular to the PWA-type printhead 18. Typically, the paper 14 moves under the PWA-type printhead 18 only in one direction as shown. While the paper 14 moves, ink droplets are ejected through nozzles (not shown) of the PWA-type printhead 18 on the paper 14 to print a desired image. Once a portion of the paper 14 has moved under the PWA-type printhead 18 and data is printed on the portion, the PWA-type printhead 18 cannot print again on that portion of the paper 14.
Referring now to FIGS. 2A and 2B, exemplary arrangements of nozzles of the scanning-type printhead 10 and the PWA-type printhead 18 are shown, respectively. The resolution of inkjet printers depends on factors including the arrangement of nozzles on printheads. For the purposes of this discussion, only a portion 11 (shown in FIG. 1A) of the scanning-type printhead 10 and a portion 19 (shown in FIG. 1B) of the PWA-type printhead 18 are enlarged and shown in FIGS. 2A and 2B, respectively.
In FIG. 2A, nozzles 20 of the scanning-type printhead 10 are arranged in columns 22. The scanning-type printhead 10 that can print a plurality of colors (e.g., black (BL), cyan, magenta, and yellow (YL)) may have one or more columns 22 of nozzles 20 per color. The number of columns 22 per color may vary depending on the resolution desired. For example, one column 22 per color may provide a resolution of 300 dots-per-inch (dpi). To obtain resolutions greater than 300 dpi (e.g., 600 dpi, 1200 dpi), more columns 22 may be added. For example, a resolution of 600 dpi may be obtained with two columns 22, a resolution of 1200 dpi may be obtained with three columns 22, and so on.
For a particular color, each additional column 22 is offset (indicated by dotted line 24) relative to other column or columns 22 for that color. Ink droplets ejected from nozzles 20 of C mutually offset columns 22 land closer together on the paper 14 than ink droplets ejected from nozzles 20 of (C-1) columns 22 thereby increasing the resolution, where C is an integer greater than 1. The number of nozzles 20 per column 22 may vary depending on the dimensions of the scanning-type printhead 10. The nozzles 20 may have a diameter “d.” Typically, the diameter is 1 mil (i.e., 1/1000th of an inch or 25.4 microns).
In FIG. 2B, the nozzles 20 of the PWA-type printhead 18 are arranged in rows 26. In some implementations, the rows 26 may be as long as the desired print area along the width of the paper 14. Depending on the desired resolution, the PWA-type printhead 18 may have one or more rows 26 of nozzles 20 per color. For each color, the rows 26 may be offset relative to one another as indicated by dotted line 28.
Referring now to FIGS. 3A and 3B, exemplary inkjet printing systems that use the scanning-type printhead 10 and the PWA-type printhead 18 are shown. In FIG. 3A, an exemplary inkjet printing system 50 that uses the scanning-type printhead 10 is shown. The inkjet printing system 50 comprises a printer control module 52 having a host interface 54, a medium control system 56, and a printhead/ink control system 58. The printer control module 52 controls the operation of the inkjet printing system 50 via the medium control system 56 and the printhead/ink control system 58. The printer control module 52 communicates with a host (not shown) via the host interface 54.
The medium control system 56 comprises a medium control module 60, medium axis motor 62, a medium roller 64, and a medium diagnostic module 66. The medium control module 60 communicates with the printer control module 52 and controls the motion of the medium (e.g., the paper 14) by controlling the medium axis motor 62. The medium axis motor 62 moves medium roller 64 that moves the paper 14 along the medium axis 16. The medium diagnostic module 66 diagnoses any faults in the medium axis motor, detects problems with the movement of the medium roller 64, and detects paper jams. The medium diagnostic module 66 reports error-codes to the medium control module 60.
The printhead/ink control system 58 comprises a printhead control module 68, a printhead axis motor 70, the scanning-type printhead 10, a printhead diagnostic module 72, an ink control module 74, and ink supply 76. The printhead control module 68 communicates with the printer control module 52 and controls the motion of the scanning-type printhead 10 by controlling the printhead axis motor 70. The printhead axis motor 70 moves the scanning-type printhead 10 along the printhead axis 12. Additionally, the printhead control module 68 generates nozzle firing signals that fire or activate the nozzles 20 of the scanning-type printhead 10. The printhead control module 68 controls the firing or activation of the nozzles 20 by controlling the timing of the nozzle firing signals.
The printhead diagnostic module 72 diagnoses any problems in the scanning-type printhead 10 and reports errors including any malfunctioning nozzles to the printhead control module 68. The ink control module 74 communicates with the printer control module 52 and controls the supply of ink to the scanning-type printhead 10 from the ink supply 76.
FIG. 3B illustrates an exemplary inkjet printing system 100 that uses the PWA-type printhead. The inkjet printing system 100 comprises a printer control module 102 having a host interface 104, a medium control system 106, and a printhead/ink control system 108. The printer control module 102 controls the operation of the inkjet printing system 100 via the medium control system 106 and the printhead/ink control system 108. The printer control module 102 communicates with a host (not shown) via the host interface 104.
The medium control system 106 comprises a medium control module 110, medium axis motor 112, a medium roller 114, and a medium diagnostic module 116. The medium control module 110 communicates with the printer control module 102 and controls the motion of the medium (e.g., the paper 14) by controlling the medium axis motor 112. The medium axis motor 112 moves medium roller 114 that moves the paper 14 along the medium axis 16. The medium diagnostic module 116 diagnoses any faults in the medium axis motor, detects problems with the movement of the medium roller 114, and detects paper jams. The medium diagnostic module 116 reports error-codes to the medium control module 110.
The printhead/ink control system 108 comprises a printhead control module 118, the PWA-type printhead 18, a printhead diagnostic module 122, an ink control module 124, and ink supply 126. The printhead control module 118 communicates with the printer control module 102 and controls the PWA-type printhead 18. The printhead control module 118 generates nozzle firing signals that fire or activate the nozzles 20 of the PWA-type printhead 18. The printhead control module 118 controls the firing or activation of the nozzles 20 by controlling the timing of the nozzle firing signals.
The printhead diagnostic module 122 diagnoses any problems in the PWA-type printhead 18 and reports errors including any malfunctioning nozzles to the printhead control module 118. The ink control module 124 communicates with the printer control module 102 and controls the supply of ink to the PWA-type printhead 18 from the ink supply 126.